Hello,
I live near the abbey of Westvleteren and you must order by phone for 1 crate and this you can only do it once every 60 days. But when you go to the abbey, there's a bar "Ten Vrede" where you can drink the beer and there's also a little shop where they sell beer,glasses,cheese and others.You can buy daily 6 bottles, so when you go in a group of, say 3 people, you can take 12 bottles and the next day and so on.In some shops like "de biertempel" in bruges or brussels you can also find it but you gonna pay 3 times the price, the same in the few bars that are permitted to sell West-Vleteren.So it depends of how many days you'll stay in Belgium and if you stay far from the monastery.